Fluid motor



June 22, 1965 H. W. SCHOLIN FLUID MOTOR Filed Jan. 4, 1963 INVENTOR. HAROLD W. S HOL\N M 0-w- FLH 5- United States Patent 3,190,077 FLUID MOTOR Harold W. Schoiin, Chicago, Ill. (1225 N. Northwest Highway, Park Ridge, 11].) Filed Jan; 4, 1963,'Ser. No. 249,474 3 Claims. (Cl. 60-545) This invention, in general, relates to fluid motors and, more particularly, relates to fluid motors in which fluid pressure is employed to drive a piston. The invention, more particularly, pertains to an air-operated fluid motor utilizing a hydraulic control piston and system for regulating the rate of movement of the piston.

Air-operated motors with the hydraulic dash pot are known in the art. This invention relates to improvements in the structural design of ajrfoperated motors. .One of these improvements pertains to the improvement in the design of the hydraulic fluid system used to regulate the rate of travel of the air-driven piston. Another aspect of the invention relates to the use of a free floating, balancing piston in a chamber separate from the chamber containing the air-driven piston. Still. another aspect'of the invention relates to the connecting portion of the hydraulicfluid system between the two chambers and the provision of adjustable means for regulating the fluid flow through the connecting portion. Another aspect of the invention pertains to a venting system for the air-driven piston and the balancing piston. 1

It is, accordingly, a primary object of this invention to provide improvements in structures of piston type airoperated motors having a hydraulic system built therein; another object of the invention being to provide improvements in air-operated motors employing a hydraulic dash pot wherein the rate of travel of an air-driven piston is regulated by the hydraulic system; another important obfor air-operated motors in which a free floating, balancing piston is utilized.

Still another object of the invention is to provide improvements in means for regulating the rate of flow of hydraulic fluids in air-operated hydraulic dash pot fluid motors; another object being to provide improvements in structures providing separate chambers for reciprocal movement of the air-driven piston; and the balancing piston and also in structures providing hydraulic fluid communication between the two chambers; another object of the invention being to provide. venting means for venting air and/ or fluid which escapes past sealing rings of the air-operated piston and/or the free floating, balancing piston.

The foregoing and numerous other important objects,

3,190,077 Patented June 22, 1965 ends threaded in the ends of the hollow cylinder 1. Each of the end walls 2, 3 has a lip portion which extends into the hollow cylinder 1, in which lip portion is provided an annular groove 9 in which is seated an air seal ring 10 to prevent the escape of air between the joint of the hollow cylinder .1 and the end walls 2, 3. The end wall 2 has an axial bore 11, in the wall of which there is a ring groove 12 in which is sea-ted an air seal ring 13. p The air seal ring 13 prevents the escape of air between the wall of the bore 11 and the shaft 14 of the air-driven piston.

The shaft 14 has an end 15 of reduced diameter, which includes a threaded portion 16 upon which is threadedly mounted the disc-shaped, air-driven piston head 17. The piston head 17 has a groove 18 in which is mounted an oil seal ring 19 for preventing the escape of oil between the shaft 14 and the piston head 17. The cylinder wall of the piston head 17 has two piston ring grooves 20 in which are mounted an oil seal ring 21 and an air seal ring 22 of similar character and purpose to tthe seal rings heretofore described. j

At substantially the mid-point of the hollow cylinder 1 there is provided a disc-shaped separator wall 23 hav- 'jectof the invention being to provide a hydraulic system advantages, and inherent functions of the invention will become apparent as the same is more fully understood from the following description, which, taken in connection with the accompanying drawings, discloses a preferred embodiment of the invention.

In the drawing: The figure is a longitudinal, diametric section of an airoperated motor of the invention with a hydraulic dash pot.

Referring to the drawing, the air-operated motor comprises a hollow cylinder 1 of uniform diameter. The cylinder 1, in conjunction with the disc-shaped end walls 2, 3

cylinders 1 by means of a plurality er bolts 8 having their ing an axial bore 24 in the alignment with axial bore 11. These two axial bores form the journal for reciprocal sliding movement of piston rod 14. The wall of the axial bore 24 has a ring groove 26 in which is'provided an oil seal ring 27 for preventing the escape of hydraulic fluid across the separator wall 23 between the bore 24 and thepiston rod 14. In some instances, this oil seal ring 27 may be omitted so long as there is a substantially tight fitbetween the axial bore 24 and piston rod 14.

Y The separator wall 23 is fixedly positioned in the hollow cylinder '1 by the use of a mounting ring 28 and the connection of the mounting ring 28 and the separator Wall 23 by means ofa plurality of bolts-29. The bolts 29 are tightened until the mounting ring 28 and the sep arator wall: 23 are drawn tightly against mounting rings '30, 31, the latter beiing positioned in grooves in the inner surface of the hollow cylinder 1.

The mounting ring 30 has an axial hole 32 large enoughto accommodate the hub 33 of the free floating or balancing piston 34. The latter is slidable with respect to the piston rod 14. l

The separator wall 23 divides the hollow cylinder 1 into a drive piston chamber 36 and a balancing piston chamber'37 in which the aforesaid pistons reciprocate,

respectively, thereby separating the chambers 36 and 37 posite sides of the pistons 17 and 34, the spaces 36a and 37a extending, respectively, between the pistons and the end walls 3 and 2, while the-spaces 36b and 3717 are disposed, respectively, between the pistons and the separator wall 23. The circular, outer edge of the piston 34 has a ring groove 38 and another ring groove 39 in which are mountedQrespectively', an air seal ring 40 and an oil seal ring 41. I

The axial bore 42 of the balancing piston 34 has a ring groove 43 and a second ring groove 44 in which .groo'ves'are mounted, respectively, anair seal ring 46 an oil seal groove 48 in whichis mounted an oil seal ring. 49; I

' The chambers 36!; and'37b are in hydraulic fluidc ommunication via a valve chamber 50 positioned onthe outer side. of the hollow cylinder 1=by any suitable means, e.g., bolts, screws orithe like (not shown). The valve chamber 5t) comprises ahead 51 having an axial passage 52'therein,

In the" wall of the hollow cylinder 1, beneath the valve chamber 50, there are provided two hydraulic fluid ports 53, 54. The ports communicate with passages 56, 57 in V V l' 3 4 the head 51, the latter passages also intercepting and communicating with the axial passage 52. Thus, hydraulic fluid can be forced from space 36b via the valve chamber 50into the space 37b or'viceversa when either of the pistons 17 or 34 are driven by pressurized air admitted to the spaces-36aor 37a. The joint between port 53 and passage 56 and the joint between port 54 and passage 57 are sealed against hydraulic fluid loss by the use of 011 seal rings 58. a The axial passage 52 in the valve chamber. 50 has a needle valve 59 movable axially therein. The needle valve has a threaded shank 60 mounted in the tapped segment 61 of the axial passage 52. A head 62 for rotating the needle valve is provided on the outer;end of the threaded shank 60. The head 51 may have another tapped hole 63 in which is threadedly mounted a filler cap 64. The shank of the needle valve 59 may have an oil seal ring 65 to seal the space between the shank of the needle valve" and the axial passage 52 against hydraulic fluid loss. V

The tip of the needle valve .59 is. positioned in the proximity ofthe passage 56 so thatit may be used to decrease or increase the effective area open to flow of hydraulic fluid out of the passage 56 into passage 52, or .vice versa. 'Thus, the needle valve 59 can be used to adjust the maximum flow rate of hydraulic fluid from the space 36b via valve chamber 50 in the space 3711'.

Assuming the fluid motor operates with a power or work stroke when pressurized air is admitted to the air passages 5, 7, the drive piston 17 moves on the work stroke toward theseparator wall 23. As it moves, the piston 17 vforces oil from space 36b, through the ,valve chamber and into the space 37b on the side ofrthe balancing piston closest to the separator wall 23. Inasmuch as the balancing pistonhas a'displacement equal to the displacement of hydraulic fluid by the drive piston 17, the balancing. piston moves away from the wall 23' ata linear rate substantially equal to the linear rate of-travel ofthe piston 17;

piston rod '14, there is little relative motion between the rod and the balancing piston. Airin the chamber 37a the threaded shank portion 73. The end of reduced diameter of the piston rod 14 has radial passage 67 communicating with vent passage, 66 and a circumferential vent groove 68. The vent groove 68, in turn, commumcates with one or more radial vent passages 69 in the piston head 17 whereby air escaping past air seal rmgs 22 can be vented to the atmosphere via the aforesaid passages.

The piston rod 14 has another radial vent'passage 70 intercepting the axial passage 66 and opening into a vent ring groove 71 in the bore 42 of the balancing piston 34. Radial vent passage or passages 72 communicatethe'outer edge of the balancing piston 34 between airseal ring 40 and oil seal ring 41 and the ring groove 71. Furthermore, inasmuch as the balancing piston 34 and the piston rod 14 do not move precisely together and inasmuch as the balancing piston may shift slightly with the loss of small amounts of hydraulic fluid in the system, the ring groove171 has a width suflicient to always keep it in communication with the'vent passage 70 of the piston rod 14;-

Thus, the function of the hydraulic system, including the needle or throttle valve 59, is to provide a hydraulic control of the rate of linear motion of the drive piston by pressurized air (or other suitable gas). The hydraulic system may exert its control influence, both during the drive stroke and the return stroke'of the piston 17. Normally, however, the control influence is usually desired only on the drive stroke. In such case, the separator wall 23 may be provided with an axial. passage 74 having a tapered endin which issea'ted a ball check 76.: The ball is pressed into the tapered opening by. means ofa coil spring 77, one end of which bears against the ball 76 and the.

" other end of which bears against the ring 78 attached to -Though the, balancing piston 34 is not attached to the V vented via the passages 4, 6. For the return stroke of .both pistons, pressurized air is admitted throughpassages 4, 6 to drive piston 34 toward separator wall 23. 1 The by draulic coupling of pistons 34 and 17; causes piston 17 to move toward end wall 3; Air is vented'from'the space 36a-through passages 5, 7.

The balancing piston 34 serves several functions; First,

it is the moving wall of an expanding-or contracting chamberfor hydraulic fluid traveling between space 3611 and space 371). Second,'it can be driven by air pressure admitted through ports 4, 6 to reset or returnthe drive tions of chambers 36 and 37 are completely filled with hydraulic fluid, as is the valve chamber 50, via fill'hole 63. Itthere isa hydraulic fluid'loss during operation of fluid motor, the balancing piston will slowly drift in its recip- :rocating path closer tothe'separatorwall 23 than was the .case of the path of movement of the balancing piston 34 before the loss of hydraulic fluid to compensate for the decrease intheiactual'.volumelof oil contained in the hydraulic system of the mot-on;

The drive piston 17 and the balancing piston 34 are :both vented so as to prevent air which leaks past the air seal rings from entering thehydraulic fluid system. The

venting system'comprises an'axial vent passage 66in'the pistonrod 14,= one end of whichnvent passage communicates with theatmosphere, e.g;, through theend of the separator wall 23 about the passage 74. The check valve allows the oil to flow more rapidly from space 37b to space 36b during the return stroke and also decreases the amount of heat generated in forcing the oil from space 7 37b to space 36b during the return stroke;

In addition to the advantages of the hydraulic meters; of the invention heretofore described, the hydraulic motors of the invention are advantageousbecause of the concentric design which conserves on space required and cost of construction. It, furthermore, provides full force on the piston and piston rod' assembly of the pressurized air by introducing the pressurized air against the full face of the pistons ,in the largest cylinder bore of the fluid motor cylinder. Additionally, the hydraulic system of the fluid motor operates with contact of the hydraulicfluid with,

the cylinder wall which previously had been contacted by'compressed air with the advantagethat the air serves to cool the cylinder wall during each pump cycle and helps to'dissipate heat developed in the hydraulic fluid during the operation ofthe fluid motor, The valve chamber 50 may be a compact, integral unit with the motor cylinder, although it is within the contemplation of the invention to have the valve chamber spaced from the cylinder and connected therewith by suitable hoses and couplings.

The fluid motors of the modern day automatic and semi-automatic machinery or equipment. The fluid motors'of the invention may be. used to advantage as servomotors on automaticboring or are many other servo-motor applications for the hydraulic fluid control systems of the compressed air-operated motors of the invention.- e i Furthermore, the structure and structural arrangement of parts employed'in the fluid motors of the invention can invention. For example, instead of onepassage'in each, of the cylinder 1 for admitting compressediair" v and venting air, a separate compressed air'entry paissage and vent passage, each with appropriate check valves, may 1' be used. Also, the hydraulic fluid passage betweenlhe. f hydraulic fluid-containing portions of cylinders or ch'am end wall invention have many uses in bers 36, 37 may be a passage through partition or separator wall 23 instead of a passage around the partition wall, i.e., the passage through valve body 50. The illustrated passage means, however, is preferred, especially when a valve or the like is employed to vary the resistance to hydraulic fluid flow between the chambers or cylinders 36, 37.

It might also be mentioned that the piston rod 14 may extend through end wall 3 as well as through partition wall 23, balancing piston 34 and end wall 2. This alternative arrangement, however, reverses the direction of the power stroke of the driven element (not shown) attached to end 73 of piston rod 14 from a direction away from the fluid motor to a directiontoward thefluid motor. Furthermore, some of the effective face area of the piston against which the compressed air acts is lost by virtue of the occupancy of the central portion of that face by the piston rod.

It is further possible to change one or both of the hydraulic fluidcontaining cylinder portions of cylinder 1 from the sides of the pistons facing the partition wall 23 to the sides of the pistons remote therefrom, which changes are also accompanied by revisions of the compressed air supply and air vent passages and also of the hydraulic passage means communicating the hydraulic fluid-containing portions of the cylinder.

It is thought that the invention and its numerous attendant advantages will be fully understood from the foregoing description, and it is obvious that numerous changes may be made in the form, construction and arrangement of the several parts without departing from the spirit or scope of the invention, or sacrificing any of its attendant advantages, the forms herein disclosed being preferred embodiments for the purpose of illustrating the invention.

The invention is hereby claimed as follows:

1. In a fluid-operated motor, the combination comprising a hollow cylinder, a partition wall mounted in said hollow cylinder and dividing the space therein into a first chamber and a second chamber, an end Wall closing each end of said cylinder, a pressurized air-operated piston reciprocable in said first chamber, pasage means for alternately admitting and venting air into and from said first chamber, said partition wall and said end wall of said second chamber each having an axial bore, a piston rod extending through said bores and attached at one end to said piston, a free floating piston reciprocable in said second chamber, said free floating piston also having an axial bore through which said piston rod extends, said free floating piston and said piston rod unattached to each other, each of said pistons having a radial vent passage in communication with radial vent passages in said piston rod, said last-mentioned radial vent passages intercepting an axial vent passage in said piston rod, and said bore of said floating piston having a .ring groove therein which is intercepted by the radially outer end of one of said radial vent passages in said piston rod and which is also intercepted by the radially inner end of the radial vent passage in said free floating piston, the cylinder. wall of said first chamber having a radial passage therethrough near said partition wall, the cylinder wall of said second chamber having a radial passage therethrough near said partition wall, a valve body mounted on the outside of said cylinder wall over said last-mentioned radial pasasges, fluid passage means in said valve body communicating said last-mentioned radial passages, and a valve on said valve body having a movable member for varying the rate capacity of hydraulic fluid flow between said first chamber and said second chamber.

2. In a fluid motor, the combination comprising a first cylinder, a second cylinder, a reciprocable piston in said first cylinder, a piston rod attached to said piston, a free floating piston in 'said second cylinder, hydraulic fluid passage means communicating said first cylinder and second cylinder, the space in said first cylinder on one side of said piston, the space in said second cylinder on one side of said free floating piston, and said hydraulic fluid passage means being filled with hydraulic fluid, and means for alternately admitting compressed air and venting said cylinders on the other sides of the respective pistons whereby said first-mentioned piston may be driven in its power stroke by compressed air admitted to said first cylinder at a speed of said piston under the control influence of flow of hydraulic fluid from said first cylinder to said second cylinder and whereby said first-mentioned piston may be driven on its return stroke by compressed air admitted to said second cylinder, an air seal ring on each of said pistons sealing the space between the edge of the piston and the cylinder wall, an oil seal ring on each of said pistons sealing the space between the edge of the piston and the cylinder wall, an axial vent passage'in said piston rod, and vent passage means communicating said axial passage and the edges of said pistons between said seal rings of each piston.

3. In a fluid-operated motor, the combination comprising a hollow cylinder divided by a transverse partition wall into a first cylindrical chamber and a second cylindrical chamber of substantially the. same diameters, an end wall closing each outer end of said chambers, a pressurized airoperated piston reciprocable in said first chamber, passage means for alternately admitting and venting air into and from the space in said first chamber between said piston and said end wall of said chamber, said partition wall and said end wall of said second chamber each having an axial bore, a piston rod extending through said bores and attached at one end to said piston, a free floating piston of substantially the same diameter as said first-mentioned piston and reciprocable in said second chamber, said free floating piston having an axial bore through which said piston rod extends, seal means in said lastmentioned bore and sealing the space between said bore and said piston rod, said seal means being axially slidable relative to said piston rod, passage means for alternately admitting and venting air into and from the space in said second chamber between said free floating piston and said end wall of said second chamber, hydraulic fluid passage means communicating the spaces in the respective chambers between their respective pistons and said partition wall, hydraulic fluid filling said last-mentioned spaces and said fluid passage means, additional passage means through said partition wall providing for direct hydraulic fluid flow through said wall between said last-mentioned spaces, and check valve means in said additional passage means allowing said'direct, hydraulic fluid flow in only one direction.

References Cited by the Examiner UNITED STATES PATENTS 706,688 8/02 Reynders et al -5 1 X 791,075 5/05 Carpenter 6054 2,192,909 3/40 Hoflar 60-54.5 X 2,691,962 10/54 Johnson 60-545 2,852,965 9/58 Wallace 6054.5 X 2,892,313 6/59 Hansberg 60-545 3,005,444 10/61 Steibel 60-545 7 FOREIGN PATENTS 165,478 10/55 Australia.

'JULIUS E. WEST, Primary Examiner. ROBERT R. BUNEVICH, Examiner. 

1. IN A FLUID-OPERATED MOTOR, THE COMBINATION COMPRISING A HOLLOW CYLINDER, A PARTITION WALL MOUNTED IN SAID HOLLOW CYLINDER AND DIVIDING THE SPACE THEREIN INTO A FIRST CHAMBER AND A SECOND CHAMBER, AN END WALL CLOSING EACH END OF SAID CYLINDER, A PRESSURIZED AIR-OPERATED PISTON RECIPROCABLE IN SAID FIRST CHAMBER, PASSAGE MEANS FOR ALTERNATELY ADMITTING AND VENTING AIR INTO AND FROM SAID FIRST CHAMBER, SAID PARTITION WALL AND SAID END WALL OF SAID SECOND CHAMBER EACH HAVING AN AXIAL BORE, A PISTON ROD EXTENDING THROUGH SAID BORES AND ATTACHED AT ONE END TO SAID PISTON, A FREE FLOATING PISTON RECIPROCABLE IN SAID SECOND CHAMBER, SAID FREE FLOATING PISTON ALSO HAVING AN AXIAL BORE THROUGH WHICH SAID PISTON ROD EXTENDS, SAID FREE FLOATING PISTON AND SAID PISTON ROD UNATTACHED TO EACH OTHER, EACH OF SAID PISTONS HAVING A RADIAL VENT PASSAGE IN COMMUNICATION WITH RADIAL VENT PASSAGE IN SAID PISTON ROD, SAID LAST-MENTIONED RADIAL VENT PASSAGES INTERCEPTING AN AXIAL VENT PASSAGE IN SAID PISTON ROD, AND SAID BORE OF SAID FLOATING PISTON HAVING A RING GROOVE THEREIN WHICH IS INTERCEPTED BY THE RADIALLY OUTER END OF ONE OF SAID RADIAL VENT PASSAGES IN SAID PISTON ROD AND WHICH IS ALSO INTERCEPTED BY THE RADIALLY INNER END OF THE RADIAL VENT PASSAGE IN SAID FREE FLOATING PISTON, THE CYLINDER WALL OF SAID FIRST CHAMBER HAVING A RADIAL PASSAGE THERETHROUGH NEAR SAID PARTITION WALL, THE CYLINDER WALL OF SAID SECOND CHAMBER HAVING A RADIAL PASSAGE THERETHROUGH NEAR SAID PARTITION WALL, A VALVE BODY MOUNTED ON THE OUTSIDE OF SAID CYLINDER WALL OVER SAID LAST-MENTIONED RADIAL PASSAGES, FLUID PASSAGE MEANS IN SAID VALVE BODY COMMUNICATING SAID LAST-MENTIONED RADIAL PASSAGES, AND A VALVE ON SAID VALVE BODY HAVING A MOVABLE MEMBER FOR VARYING THE RATE CAPACITY OF HYDRAULIC FLUID FLOW BETWEEN SAID FIRST CHAMBER AND SAID SECOND CHAMBER. 